This invention relates to a process for the separation of a butene mixture to produce a n-butene rich product and an isobutylene rich product in a fractionator wherein a portion of the fractionator overhead is isomerized and the entire isomerization effluent is introduced into the fractionator at a locus below the locus of the reflux. The resulting high purity streams and isobutenes are useful in subsequent reactions to produce secondary butyl alcohol and methyl ethyl ketone from normal butylene and butyl rubber and lubricating oil additive from isobutylene.
The isomerization of olefins is generally well known in the petroleum refining art. The double bonds present in olefinic hydrocarbons shift readily over various catalysts to a more central position in the organic molecule. Compositions of a metal from Group VIII of the Periodic Table, properly inhibited in their hydrogenation activity, with a refractory inorganic oxide are well known catalysts in producing olefinic bond migration.